Fire and temperature alarm or indicator.



PATENTED APR. 16, 1907.

G.'L. SMITH.

FIRE AND TEMPERATURE ALARM OR INDICATOR.

APPLICATION FILED JULY23,19064 ill/4 I: 25

pressed air, the tube communicating with a UNITED STATES PATENT OFFICE.

GEORGE LAWRENCE SMITH, OF ABERDEEN, SCOTLAND.

FIRE AND TEMPERATURE ALARM OH INDICATOR- Specification of Letters Patent.

Application filed July 23. 1906. Serial No. 327,286.

No. 850,681. Patented April 16,1907.

To all whom it may concern." lator would be adjusted. Such an appa- Be it known that I, GEORGE LAWRENCE ratus would not attain the objects sought by SMITH, a subject of the King of Great Britthis invention, because even supposing the ain, residing at Aberdeen, Scotland, North tube to contain air the air would be ex- Britain, have invented certain new and usepanded upon a gradual rise of temperature as ful Improvements in Fire and Temperature I well as upon a sudden rise, and therefore if Alarms or Indicators, and of which the folthe temperature of the room or place in lowing is aspecification. I which the apparatus was fitted rose slowly The object of this invention is to provide a through any ordinary heating in a normal pneumatic fire and tem erature alarm or ini manner the ventilator would beoperated, or, dicator which shall fulf certain conditions- 5 substituting for the ventilator a fire-alarm that is, it must not be merely a local firecircuit, the fire-alarm would be sounded at alarm, but an ap aratus which must extend 1 any gradual or ordinary rise of temperature. over a considerab e area+so as to indicate a N ow according to this invention a metal rise in temperature at any part of the room tube of small diameter is provided of any reor rooms through which it passes, and at the quired length and having a correspondingly same time it must not indicate upon a gradsmall bore. The tube is closed at one end ual rise, but only upon a sudden rise, in temand at the other is connected with a pneuperature. Further, it must be of such a conmatic pressure-indicator, which when the struction that the electrical'contacts which air expands in the tube acts to close an are to be operated must be capable of being electric circuit and to operate an alarm. placed even outside the area within which The air within the tube and within the pneuthe'sudden rise of temperature takes place or matic pressure-indicator is to be' normally is likely to take place. -maintained at atmospheric pressure, and to Now it has been heretofore proposed to this end I provide the tube with an air-vent construct a pneumatic local fire-alarm appaor small opening for the passage of the air, so ratus composed of a closed expansible-metal that upon the in the tube expanding by a box containing air provided with a porous normal and slow rise of temperature the air plug calculated to permit of a slow entrance will escape by the vent sufficiently to insure or exit of air to or from the box, so that the the maintenance of atmospheric pressure box only was expanded upon a sudden rise in within the tube, but upon a sudden rise, temperature, while upon gradual rises the air owing, for instance, to a fire, the capacity of escaped by the porous plug. The expansion the air-vent will not be suficient to keep of the box closed or opened an electric cirpace with the expansion, and conseeuently cuit. In practice such an apparatus posthe pneumatic pressure-indicator will act, sessed serious disadvantages in that it was the electric circuit will be closed, and the not capable of indicating over a large area, alarm sounded. At the same time with such and therefore to indicate a fire throughout a an apparatus it is essential that the pneunumber of rooms or a building it was necesmatic pressure-indicator should be oi the sary to'afiix a number of these expansible smallest practicable capacity, so that it may boxes, and beyond this the electrical conbe afiected with certainty by the expa'nsioh tacts and conductors were extended actually oi the air in the small-bore tube. into the room or places in which a fire was to Examples of construction of the invention be indicated. are illustrated in the accompanying draw- In operating dampers or ventilators by ings, whereon action brought about by changes of tempera- Figure 1 is an elevation showin the airture it has been proposed to employ a tube containing tube, which is extends through containing water under pressure or comor around the place or placesin which any unusual or sudden rise of temperature is to be notified, and illustrates the tube connected with a pressure-indicator, and an electric circuit is indicated in diagram by dotted lines, Fig. 2 being a vertical cross-section taken through the pressure indicator, While Fig. 3 is a cross-section, on a larger scale than the previous figures, showing the adjustable cylinder having a,piston under spring-pres sure, and then the tube could be extended around a room, for instance, so that upon any rise of temperature, however gradual or however sudden, an expansion of the liquids in the tube would takeplace, the piston would be operated, and the damper or ventia modified construction orthe pressure-inchcater.

Referring to Figs. 1 to a, the thermostatic alarm-tube 1 is 'made of copper, although other'metal may be used, and it is of comparatively small bore-say about one-tenth of an inch diameterwith the bore of, say, one-twentieth of an inch, although these dimensions may be increased or decreased both as regards the diameter and the bore to suit special conditions. The tube is fitted around or through the room or rooms to be protected, say as near the ceiling or roof as convenient, and in dWelling-houses itrnay be dropped into the picture-molding commonly fitted, and in such positions the tube would be invisible. lln fitting a number of rooms a comparatively large tube may be employed say one-eighth of an inch in dia1neterbut the connections between room and room and between the rooms and the pressure-indicatorwhich may be far removed can be con structed with a tube of small diameter, as inslower, although with equal certainty, so

that the mechanical conditions to be met with in different situations thus have an iniluence on the size, strength, and thickness of the tubing it is preferable to employ. lhe tube 1 is closed at one endsay at 2, as shown in the drawingsand at the other and open end 3 it isconnected with the pressure-indicator.-

The indicator (shown at Figs. 1 to 1) is connected to a plate 4, so that the tube communicates with a passage 5 in the said plate, the passage 5 communicating With the interior of an expansible chamber 6, which may have a flexible or elastic diaphragm '7, upon which there rests a platinum or other contact 8, carried by a light spring 9 from a stud 10, r I i L nxed upon the plate -1. Above the contacpoint 8 is a bridge-piece 11, fixed to the base 12 of the indicator and carrying an adjustable contact-screw 13, so that when the pressure of air is increased in the tube 1 and passes by the passage 5 the expansion of the case ("3 causes the platinum contact 8 to touch the contact-screw 13 and complete the circuit.

The bridge-piece 11 has a terminal 1-1 mountbattery and 18 any suitable or well-known alarm apparatus operated by the current passing through the circuit 16.

As aforesaid, I provide a vent, generally controllable or adjustable. through which the air from the tube may slowly escape from or press into the tube at any gradual or usual Variation of temperature, and in the drawings, Figs. 1 and 4, such vent is composed by a hole formed in the wall of the passage 5 and communicating therewith. 1n the construction illustrated a screw 19, entering the hole, as shown in detail at Figs. 3 and 4, is formed with a groove 20, and .beneath the head of the screw is a washer 21 of porous materiahsuch as porous paper, cloth, or the like.

22, Figs. 1 and 2,- is a screw-plug closing a hole in the plate 4, communicating with the passage 5, which screw 22 can be removed and replaced by a suitable testing-machine, sothat by forcing a certain quantity of air into the passage 5 in the tube 1 the ,efl'cct of a fire or sudden rise of temperature can be produced to set oil the alarm for thepurpose of testing the apparatus.

Obviously the construction of the devices for controlling the vent communicating with the bore of the. tube 1 can be infinitely varied;

but ll would have it understood that in some cases ni eansfor controlling this vent may be dispensed with, a simple perforation being suflicient to allow the air to pass from or into the tube upon any usual orordinary variation of temperature. It will now be understood that upon an unusual or sudden rise of temperature, due to a fire or other causes, the air in the tube 1 will become expanded and the pressure will be communicated to the indicator, and in the construction shown at Figs. 1 to 4 it will act within the expansible case 6 and cause the electrical contacts to close, so completing the circuit 16 and sounding the alarm.

At Figs. 5 and 6 is shown a modified form of what I have termed the pressure-indi- 'cator, consisting of a box 23 equivalent to the passage 5 and fitted with a test-screw 24 and formed with a hole communicating with the outer atmosphere, which can be adjustably controlled by a screw 25. The box 223 communicates by a tube 26 with a closed case 27, containing mercury.

28 is a tube (which may be of glass) which enters the closed case 27, dipping beneath the surface 01" the mercury, and in this lube there are two platinum contacts, as indicated, the upper end of the tube being open and turnei'l down to exclude dust. The platinum contacts are connected by terminal screws 29 to a wire 36,1orming an electric circuit, 31 indicating battery and 322 any suitable electrically-operated alarm apparatus.

When the air in the tube 1 is unusually or suddenly heated by fire or otherwise, the

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case 27 Will have sunk below the lower end of the said tube, and any further pressure of air will simply pass through the contained mercury inthe enlarged part of the tube 28.

What I. claim as my invention, and desire to secure by Letters Patent, is

1. In I fire and temperature alarms; the combination of a metal tube of small diameter having a correspondingly small bore containing air and closed at one end a closed chamber with the interior of which the open end of the tube communicates, said tube having a vent for permitting air to pass slowly to and from the bore of the tube upona gradual I and ordinary variation of temperature, and 1 means for regulating said vent, two electrical 5 contacts, means operated by a sudden and unusual increase of pneumatic pressure in the f tube and chamber for mechanically closing i said contacts, an electrical conductor having I its ends respectively electrically connected to i said contacts, and an electric battery and an alarm device located in the electric circuit composed by the conductor aforesaid substantially as set forth.

In fire and temperature alarms; the combination of a metal tube of small diameter having a correspondingly small bore contaming air, means for closing one end of said tube a plate having a passage formed therein and having an air-vent communicating with said passage, means for adjustahlyregulating the passage of air through said vent, said plate having a test-aperture communicating with said passage for testing the action of the alarm by air-pressure admitted through said test-aperture, and a screw-plug for closing the. testaperture, means for connecting the open end of said metal tube to one end of said passage in said plate, a chamber capable of expansion by interior air-pressure and hav ing a bore communicating with the passage in the plate aforesaid, a movable electric contact carried upon said expansible chan'iber, a

5 stationary electric contact, means for supporting the latter contact above the movable contact, an electric conductor having its ends respectively electrically connected to said contacts, and an electric battery and an alarm device located in the electric circuit composed by said conductor, substantially as set forth.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

iEORGE LAWRENCE SMITH. Witnesses:

JAMES WALKER, HENRY ALEXANDER BOTIIWELL. 

